I agree that the Motorola lock in was a huge turn off - to the extent that I could never see the system taking off unless Moto licenced it to other phone vendors. Of course doing so wouldn't do much for Motorola, but that's where we are now anyway.
I disagree that a bigger built in battery is preferable, because you'll never find that one size that fits all users (people never far from a car or desk have no need for a two day battery and they don't want the bulk). With battery back packs, power users can stow a spare or two without the unwieldiness of a conventional power bank, and they don't need to power cycle their phone to swap an internal battery like phones of old.
Cameras can be connected wirelessly, and indeed the Sony QX10 and QX100 (large sensors and lenses that use a phone for screen and storage) are holding their value after several years, despite the original criticism that their use of Bluetooth as opposed to a direct bus connection hampered their performance.
Wireless headsets could also make use of a shap on connection to a phone to recharge from a phone's battery.